Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 262243
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
543 PM EST THU FEB 26 2015

.AVIATION...

DRY NORTHERLY FLOW AND THE LOSS OF DIURNAL SUPPORT WILL BRING A
STEADY CLEARING TREND TO THE LINGERING LOW VFR STRATUS EARLY THIS
EVENING.  EXISTING ARCTIC HIGH PRESSURE WILL SUSTAIN A DRY/STABLE
ENVIRONMENT INTO FRIDAY.  THERE WILL BE A LIMITED COVERAGE OF
DIURNAL STRATOCUMULUS DEVELOPMENT DURING THE DAYLIGHT
HOURS...CEILINGS AT LOWER VFR PER RECENT MODEL SOUNDING DATA.  A
BACKING WIND FIELD WITH TIME...SETTLING INTO A SOUTHWEST DIRECTION
BY AFTERNOON AS THE HIGH SLIPS TO THE EAST.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM FOR CEILINGS AT LEAST INTERMITTENLY BELOW 5000 FT THROUGH
  01Z.

&&

.PREV DISCUSSION...ISSUED 335 PM EST THU FEB 26 2015

SHORT TERM... THROUGH TONIGHT

ANY LINGERING SNOW SHOWERS OVER SOUTHEASTERN PORTIONS OF THE CWA
WILL CONTINUE TO DIMINISH THIS AFTERNOON AS THE ASSOCIATED WAVE
PROGRESSES EAST.  RIDGING OVER THE NORTHERN GREAT LAKES THEN SLIDES
SOUTH OVER THE AREA ALLOWING FOR DRIER NORTHERLY AIR TO TAKE OVER
THIS EVENING INTO THE OVERNIGHT HOURS. WITH CAA MOVING INTO THE
AREA...A CLEARING TREND WILL BE SEEN LATER TONIGHT AS IS ALREADY
EVIDENT BY CURRENT SATELLITE UPSTREAM. AS THE PRESSURE GRADIENT
WEAKENS...WINDS SLACKEN OVERNIGHT BECOMING LIGHT TO CALM OVER MUCH
OF THE AREA. WITH CLEARING SKIES AND LIGHT WINDS...EXPECTING A
GOOD RADIATIONAL COOLING EVENT INTO EARLY FRIDAY MORNING. THIS
WILL BE THE MAIN CONCERN IN THE SHORT TERM WITH THE CONTINUED COLD
AND POSSIBLY RECORD BREAKING LOWS GOING INTO FRIDAY MORNING. GIVEN
LIGHT TO CALM WINDS EXPECTED OVERNIGHT...WILL NOT ISSUE A WIND
CHILL ADVISORY HOWEVER WIND CHILLS MAY TOUCH ADVISORY CRITERIA FOR
A COUPLE OF HOURS ESPECIALLY IN THE THUMB AREA.

RECORD LOWS FOR FEB 27
DETROIT AREA: -4  (1934)
FLINT AREA:   -14 (1994)
SAGINAW:      -8  (1934)

LONG TERM...

EXPANSIVE HIGH PRESSURE (1040+ MB) OVER CENTRAL CANADA EXTENDING
SOUTH INTO THE PLAINS THIS AFTERNOON...WITH THE CENTER OF THE HIGH
SLIDING THROUGH THE OHIO VALLEY VALLEY FRIDAY NIGHT. AIRMASS LOOKS
TO BE REMAINING VERY DRY (PW VALUES UNDER A TENTH)...WITH SURFACE
DEW PTS BELOW ZERO...PROVIDING FOR FAVORABLE RADIATING NIGHT (NOT
IDEAL DUE TO MODEST WINDS). MIN TEMPS SHOULD BE LOWEST TOWARD THE
OHIO BORDER...WHERE THE WEAKEST GRADIENT WILL RESIDE. INHERITED
GRIDS (ZERO TO -8 BELOW) REFLECT THIS...AND NOT PLANNING ON MAKING
ANY CHANGES. WITH FAVORABLE VERY LIGHT SOUTHWEST DRAINAGE WIND FOR
DTW...GOOD CHANCE FOR LOW TO REACH OR EXCEED THE RECORD VALUE FOR
FEBRUARY 28TH (-1 SET IN 1994). YESTERDAY AND TODAY THE LATE
FEBRUARY SUNSHINE HAS BEEN REVEALING ITS STRENGTH...WITH TEMPS
CRUISING PAST OUR FORECASTED MAXES...AS THE OLD/DIRTY SNOWPACK HAS A
REDUCED ALBEDO. WITH THAT IN MIND...WILL BE RAISING TEMPS ON
FRIDAY...AS THESE DRY AIRMASSES ARE CONDUCIVE TO INCREASED DIURNAL
SWINGS. THERE IS A LIGHT LOW LEVEL WESTERLY FLOW DEVELOPING
TOMORROW...WHICH COULD SUPPORT A MODEST CU UP...BUT WILL CARRY MAXES
UP AROUND 20 DEGREES NONE-THE-LESS. LIGHT SOUTHWEST RETURN FLOW
CONTINUING ON SATURDAY WILL SUPPORT A FURTHER WARM UP...LOW/MID
20S...BASED ON 925 MB TEMPS OF -10 TO -12 C AND FULL INSOLATION.
INCREASING CLOUDS AND WARM ADVECTION PATTERN EVENING SHOULD HOLD
MAXES IN SINGLE NUMBERS AND THEN CAUSE A RISE...WITH GOOD CHANCE OF
LIGHT SNOW DEVELOPING SATURDAY NIGHT WITH 140 KNOT JET CORE LIFTING
OVERHEAD...WITH WHAT LOOKS TO BE SUFFICIENT MOISTURE SURGE ARRIVING
TOWARD 12Z SUNDAY...WITH SPECIFIC HUMIDITIES CLIMBING AROUND 2 G/KG
AT 700 MB (PER 12Z GFS/NAM)...OR SLIGHTLY HIGHER IF ONE IS TO
BELIEVE THE 12Z EURO.  BLEND OF MODEL QPFS SUGGEST 1 TO 3 INCH
SNOWFALL FORECAST...HIGHEST TOTALS SOUTH...WITH THE EURO STILL
ADVERTISING A BIT MORE...AND THE CANADIAN MUCH LESS. THE EXACT SNOW
TO LIQUID RATIOS WILL PROBABLY HOLD THE KEY...AS AIRMASS MAY WARM UP
ENOUGH SUPPORT MORE CLIMO NORM VALUES OF 12:1 VS THE HIGHER 15-17:1
VALUES ADVERTISED.

LINGERING LOW PRESSURE FROM THE WEEKEND WILL ALLOW FOR SNOW TO
CONTINUE MONDAY MORNING INTO EARLY MONDAY AFTERNOON. NEXT SYSTEM
MOVES IN FOR TUESDAY WITH SCATTERED SNOW SHOWERS TUESDAY MORNING AND
INCREASING CHANCES OF PRECIPITATION THROUGH DAY INTO WEDNESDAY
MORNING. TEMPERATURES ARE EXPECTED TO WARM TUESDAY AFTERNOON WHICH
COULD MEAN RAIN AND SNOW MIXED OVER THE NORTHERN HALF OF THE CWA AND
RAIN OVER THE SOUTHERN HALF. TEMPS LOOK TO DROP BELOW FREEZING
OVERNIGHT TUESDAY INTO EARLY WEDNESDAY MORNING WHICH LIKELY MEANS
PRECIPITATION CHANGING OVER TO ALL SNOW LATE TUESDAY NIGHT. BY
WEDNESDAY AFTERNOON THE TEMPS REBOUND BACK INTO THE 30`S BRINGING A
REPEAT OF TUESDAY AFTERNOONS WEATHER. IT SHOULD BE NOTED THAT POPS
DROP WEDNESDAY SO ANY PRECIPITATION IS EXPECTED BE SCATTERED.

MARINE...

HIGH PRESSURE WILL BE BUILDING INTO THE OHIO VALLEY TOMORROW AND
TOMORROW NIGHT...WITH MODEST SOUTHWEST RETURN FLOW DEVELOPING AROUND
THE HIGH OVER THE CENTRAL GREAT LAKES. CENTRAL SECTIONS OF LAKE
HURON WILL PROBABLY SEE WINDS INCREASE INTO THE 15 TO 20 KNOT RANGE
..OTHERWISE WINDS REMAIN ON THE LIGHTER SIDE....WITH GRADUALLY
WEAKENING SOUTHWEST GRADIENT INTO THE WEEKEND...AS ANOTHER COLD
FRONT SLIDES THROUGH SUNDAY NIGHT.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....99
SHORT TERM...SS
LONG TERM....SF/DE
MARINE.......SF


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).



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